1. Field of the Invention
This invention relates to an automatic toilet bowl cleaner dispenser, and more particularly to a low cost automatic toilet bowl cleaning agent dispenser which self-regulates its cleaning agent output with reference to the concentration strength of a cleaning agent solution contained inside the dispenser, and to a method of manufacture thereof.
2. Prior Art
Current automatic toilet bowl cleaner dispensers are basically flexible, or rigid, containers containing a concentrated, solid cleaning agent material. Such dispensers are mounted to the toilet tank, submerged to some point beneath the tank water line. With some such dispensers a dose volume of tank water is allowed to enter the container between flush cycles, absorb some of the solid cleaning agent, and is then emitted into the tank (and ultimately into the bowl) during the next flush.
Examples of solid cleaning agents popular for this type of dispenser are concentrated chlorine materials such as calcium hypochlorite or one of the chlorinated isocyanurates, and also various surfactant/blue dye mixtures. U.S. Pat. No. 4,200,606 (Kitko) discloses examples of such solid cleaning agents.
Regardless of the cleaning agent used, there is an optimum concentration level for the cleaning agent to the toilet bowl water. Effective cleaning action does not occur below this optimum level, and cleaning material is simplY wasted when used above this optimum level.
Producers of current automatic toilet bowl cleaning agent dispensers recognize this fact, and have attempted to regulate cleaner output by constructing dispensers to emit a uniform volume of the concentrated water/cleaning agent solution contained inside the unit with each flush. Examples of such prior dispensers of the rigid body type are disclosed in U.S. Pat. Nos. 3,121,236 (Yadro), 3,618,143 (Hill), and 4,186,856 (Dirsking). Similar dispensers of the flexible body type are disclosed in U.S. Pat. Nos. 2,807,807 (Harper), 3,545,014 (Davis), and 3,869,069 (Levey).
However, a dispenser designed to emit a uniform amount of liquid with each flush of the toilet does not provide an optimum, or even uniform, output of cleaning agent with each flush. The concentration of solid cleaning agent dissolved into the water solution inside the dispenser at any given time is dramatically dependent upon the time the cleaning agent has been in contact with the water, how often and how much fresh water is added to the dispenser with each flush of the toilet, and the speed at which the cleaning agent can reach its maximum saturation point in the water under the temperature conditions present.
Current toilet bowl cleaning agent dispenser structures cannot address these factors. As a result, under the varying conditions found in use, their actual cleaning agent output levels are too high or too low as often as they are proper even though their liquid volume output is uniform. As a result, the dispenser user pays for too little cleaning part of the time, efficient cleaning part of the time, and too much cleaning part of the time.
This effect may be readily seen by examining the operation of a uniform liquid output dispenser containing a solid chlorine cleaning agent such as calcium hypochlorite. Calcium hypochlorite releases chlorine (hypochlorite ions) into the cleaning solution to produce an oxidizing action which chemically breaks down stains and soils on the toilet bowl surface. The optimum cleaning level of chlorine in the toilet bowl water is 2 to 7 parts per million for all chlorine cleaning agents. A typical conventional uniform liquid output cleaning agent having a dispenser designed for 30 days use (350 flushes) has a dispenser reservoir for 100 ml of water and a 11/2 oz. block of calcium hypochlorite, with the liquid output level set for a uniform 10 ml with each flush of the toilet.
The nonuniformity of cleaning agent dispensing over the life of such a dispenser is evident from a consideration of FIG. 1 which effectively shows the saturation time curve for calcium hypochlorite in 100 ml of water. At 70.degree. F., approximately 56 hours are required for the solution to reach a point where the molar fraction of chlorine (hypochlorite) to the water is as high as possible (a point where the water will not absorb additional chlorine). At this saturation point, 10 ml of the solution emitted into the 41/2 gallons of water in a standard toilet tank will produce a 70 ppm chlorine level as shown in FIG. 1.
With a typical use of the toilet of 12 flushes per day, the minimum effective concentration of 2 ppm chlorine would be reached within two hours of initial placement of the dispenser in a toilet tank. However, with this use the concentration would reach about 40 ppm chlorine and then gradually diminish to zero as the chlorine is used up. This results in gross overuse of the chlorine during a substantial period and insufficient use or waste of the material at the end of the use period. If the dose is reduced to reduce the maximum concentration, insufficient concentrations will be obtained for a longer period initially and at the end of the use period.
Other conventional toilet bowl cleaning agent dispensers empty their entire volumes of solution into the tank each time the toilet is flushed. Such dispensers therefore restart the saturation time curve after each flush. Thus, any time the dispenser sits for several hours or days the chlorine output for the first flush is equivalent to that required for 20 or 30 flushes, and if two or more flushes are made during a short interval (e.g. 1/2 hour) those flushes following the first flush would produce far below the minimum effective 2 ppm chlorine in the toilet.